The invention is based on an injection instant adjuster for internal combustion engines as described herein. An injection instant adjuster of this kind is already known from French Pat. No. 779,910, in which the adjusting cam is rotated by a flyweight, acting as a control element, and the relative rotary position of an off-drive element is thereby varied relative to a driving element of the adjuster. In one application of the described adjuster, the driving element is connected with the drive shaft of the engine and the off-drive element is connected with the camshaft of the injection pump, and it is only an adjustment toward "early" of the instant of injection which is controlled. In this adjuster, the maximal possible adjusting angle can be varied by means of varying the eccentricity and length of the guide groove for the adjusting bolt; or the adjusting direction can be adapted to the rotary direction of the adjuster by means of shifting the outset point of the eccentric adjusting bolt.
Adjusters for the instant of injection which are actuated by centrifugal force are also known from German Pat. No. 1,022,419 and German Offenlegungsschrift No. 27 25 414, in which the flyweights engage the adjusting cams of pairs of cams which are embodied as adjusting and compensation cams and which serve as adjusting means. These adjusters for the instant of injection, because of their structurally dictated self-locking feature, have a reduced load dependence in the event of sudden load stresses, and accordingly also have a reduced tendency to wear more or less than the adjusters described first above, and these adjusters also cause less noise. These adjusters are again designed only for controlling adjustment toward "early", and the pairs of cams are installed in such a manner, depending on the rotary direction of the adjuster, that only an adjustment toward "early" is attained.
In the known injection instant adjusters, equipped with adjusting cams, only an adjustment toward "early" can be controlled; or, if the adjusting cams are installed in a reversed position, only an adjustment toward "late" can be controlled. An adjustment of the instant of injection toward "late" which precedes the conventional adjustment toward "early" is not controlled in the known injection instant adjusters. An injection adjusting device is known from German Offenlegungsschrift No. 24 58 109, in which two injection adjusters are disposed in series, one of which is a normal injection adjuster, controlling adjustment toward "early", and the other additionally effects an adjustment toward "late" at a given switchover rpm. This system is hydraulically controlled and is extremely expensive. It is accordingly the object of the invention to control a "late" adjustment preceding the normal "early" adjustment with a single injection instant adjuster, without providing for a reversal of movement of the control element.